Pulpers



y 22, 1962 E. o. L. WALLEN 3,035,781

PULPERS Filed Nov. 25, 1959 2 Sheets-Sheet 1 FIG.1

May 22, 1962 E. o. L. WALLEN 3,035,781

PULPERS Filed Nov. 25, 1959 2 Sheets-Sheet 2 FIG.3

United States Patent 9 3,035,781 PULPERS Emil Olof Lennart Wallen, Stockholm, Sweden, assignor to Grnbbens & Co. Aktiebolag, Stockholm, Sweden, a joint-stock company of Sweden Filed Nov. 25, 1959, Ser. No. 855,365 Claims priority, application Sweden Nov. 28, 1958 7 Claims. (Cl. -241--4t5) This invention relates to a pulper comprising a con tainer with an impeller arranged therein, said impeller being provided with one or more blades.

Pulpers are used for suspending dried pulp such as sulphate and sulphite pulp, mechanical pulp, cotton pulp or semi-chemical pulp, as well as waste from cardboard, paper and pulp manufacture, and from waste paper. Pulpers are also used in many other fields.

In previously known pulpers, coherent fibrous sheets are disintegrated by a blade or impeller operating in water. In these pulpers, attempts are made to provide a turbulent motion in water or, alternatively, a grinding action between two members moving in relation to each other to provide for disintegration. Some known pulpers are also provided with knives or other sharp, cutting edges for cutting the material to pieces.

It has now proved that an effectively operating pulper should cause all of the suspended material to circulate as rapidly as possible. The water particles and the material remote from the impeller should thus as quickly as possible, i.e. in the shortest way, be conveyed to the impeller. This presupposes that the movement in the container is parallel with the impeller shaft or its extension. In the container there must therefore be produced a flow directed towards the impeller, said flow passing the impeller by which the flow is deflected and imparted kinetic energy. From the impeller the flow is, for a short dis tance, directed perpendicular to the impeller shaft and again is thereafter conveyed along the surfaces of the container parallel to the impeller shaft but in opposite direction to the aforementioned flow. At the suspension surface remote from the impeller the flow is, for a short distance, perpendicular to the impeller shaft or its extension, and thereupon the suspension is sucked towards the impeller and the circulation is completed.

Preferably no turbulent motions are created since this causes a slower disintegration of the material and involves the risk that the layer remote from the impeller does not circulate and is not conveyed to the impeller, but only rotates. Furthermore, an interior circulation is obtained by turbulent motions since the circulation path becomes longer with helical motion of the suspension than with the more rectilinear motion stated above. Thus, losses arise due to turbulent motions for which reason more power must be supplied in order to bring the entire suspension into a stable motion. This is noticeable, especially in pulping rather great quantities of material, when the apparent viscosity of such suspensions rises very quickly with increased concentration.

This ideal circulation of the suspension in a pnlper can, according to the invention, be obtained with an impeller provided with one or more blades, said impeller being arranged in the pulper, each blade extending along a helical line in relation to the impeller shaft or along a part of such a helical line and being mounted on the impeller or its shaft, the plane of at least one blade being essentially perpendicular to the shaft of the impeller at that end of the blade which is located next to the shaft, the plane of at least one blade being essentially parallel to the shaft of the impeller at the blade end which is remote from the shaft of the impeller. Each blade extends preferably continuously from the end next to the shaft to the end remote from the shaft. One or more of the 3,635,181 Patented May 22, 1962 blades are preferably extended like a corkscrew at the end adjacent the shaft and, if desired, are pointed so that paper packs or the like entrained with the suspension are pierced and disintegrated. The blades may be disposed on an impeller body which is plane, conical, pyramidal or so forth. If desired, they maybe attached to the impeller shaft proper. The best efficiency is obtained by using an impeller body in the form of a body of rotation which is streamlined.

A hydrapulper according to the invention is shown by way of example in the accompanying drawing, in which-- FIG. 1 is a top view of the hydrapulper; and

FIG. 2 is a perspective view of a detail in FIG. 1.

FIG. 3 is an elevation View of a modification of the impeller in FIG. 1.

The hydrapulper according to FIG. 1 consists of a container 1 with a centrally positioned impeller 2, a screen bottom 5, and guide means 4. As will be seen from FIG. 1, the impeller 2 is of hyperbola shape and is provided with two blades 3 which are not extended in the manner of a corkscrew and which are not interrupted. FIG. 3 shows an impeller with blades of corkscrew shape in which the blades also are uninterrupted. However, the blades may be perforated or interrupted by cut out portions, which may be displaced along the radius or radially in relation to one another. The best efiiciency, however, is obtained by using continuously extending blades according to the drawing. The width and/or thickness of the blade may also vary along the length of the blade. The operative surface of at least one blade is preferably perpendicular to the surface of the impeller body.

In order to suppress the tendency of the suspension to rotate with the impeller 2, the container 1 should advantageously be provided with guide means 4 which preferably are high. These guide means are advantageously disposed in such a manner that their planes or the extensions thereof pass through the impeller shaft or its extension. The guide means may also be disposed in such a manner that their planes next to the impeller have the same direction as the direction of movement of a particle leaving the rotating impeller.

In tests carried out in a hydrapulper of known type an effect of 30 HP. was required for a good circulation of one cubic meter of 7.5% sulphite pulp. When the impeller was replaced by an impeller according to the present invention, only 15 HP. were required for the same circulation.

What I claim is:

1. A pulper comprising a container, an,impeller supported in said container for relative rotary movement therewith, said impeller defining an axis, said impeller including a shaft portion of substantially cylindrical shape extending along said axis and a portion constituted by a body of rotation coupled to said shaft portion, the later portion having one end which is tangent to the shaft portion and having another end remote from said shaft portion which is substantially perpendicular thereto, said latter portion being smoothly rounded between said ends, said impeller including a blade extending helically along said shaft portion and the body of revolution portion, said blade having opposite ends respectively adjacent and remote from the shaft portion, the blade being substantially perpendicular to the shaft portion of the impeller at the end of the blade which is positioned adjacent the shaft portion, the blade being substantially parallel to the shaft portion at the end which is remote from the shaft portion of the impeller.

2. A pulper as claimed in claim 1, wherein the blade extends continuously from the end adjacent the shaft to the end remote from the shaft.

3. A pulper as claimed in claim 1, wherein the blade has an operative surface perpendicular to the tangent plane of the impeller body.

4. A pulper as claimed in claim 1, wherein the container includes guides means arranged substantially parallel to said axis.

5. A pulper as claimed in claim 1, wherein said impeller comprises a further blade extending helically around said shaft portion and said body of revolution portion 6. A pulper comprising a container, an impeller sup ported in said container for relative rotary movement therewith, said impeller including a shaft portion and a body portion connected end to end with said shaft portion, said portions being bodies of rotation about a common axis, said shaft portion being substantially cylindrical, said body portion being substantially of hyperbola shape and having one end substantially coextensive with said cylindrical shaft portion, the body portion having an end opposite to said one end and remote from said shaft portion, said remote end defining a plane which is perpendicular to said axis, said impeller further including a blade extending around said shaft portion and said body portion along a helical path, said blade having opposite ends, one of which is perpendicular to said axis and the other of which is parallel to said axis, said one end being adjacent said shaft portion, the ohter end being adjacent the remote end of the body portion.

7, A pulper comprising a container, an impeller supported in said container for relative rotary movement therewith, said impeller defining an axis, said impeller including a shaft portion of substantially cylindrical shape extending along said axis and a portion constituted by a body of rotation coupled to said shaft portion, the latter portion having one end which is tangent to the shaft portion and having another end remote from said shaft portion which is substantially perpendicular thereto, said latter portion being smoothly rounded between said ends, said impeller including a blade extending helically along said shaft portion and the body of revolution portion, said blade having opposite ends respectively adjacent and remote from the shaft portion, said blade at the end adjacent the shaft being extended in the form of a corkscrew, the blade being substantially parallel to the shaft portion at the end which is remote from the shaft portion of the impeller.

References Cited in the file of this patent UNITED STATES PATENTS 1,630,361 Stay et al May 31, 1927 1,741,173 Walker Dec. 31, 1929 2,665,853 Nicholson Ian. 12, 1954 FOREIGN PATENTS 278,152 Great Britain Oct. 6, 1927 

